1. Field of the invention
The present invention generally relates to a clasping device for fixing a cargo item on a base by means of a strap or for tightening a strap turned around the cargo item and, particularly, to a clasping device durable against a large load such as a large size automobile and including a means for temporarily holding the strap, having been tightened by a first tightening operation of a lever, to increasingly tighten the strap by further tightening operation of the lever.
2. Description of the prior art
The inventor of the present invention has previously provided a clasping device of this type, which is described in first Japanese patent publication No. 15679/1983 (corresponding to U.S. patent application Ser. No. 474,638 and EPC patent application No. PCT/JP82/00268, is compactly assembled and preferably used for the purpose of fixing the large size automobile of, for example more than ten tons, on a deck aboard a ship. The construction of the above clasping device will be briefly described hereinbelow with reference to FIGS. 1 to 3.
The clasping device has a clasping main assembly A which includes a body 5 and a lever 6 pivotally connected with the body 5 by means of a pair of links 7a and 7b, a first connecting member A' connected with the body 5, and second connecting member A" connected with the lever 6. The connecting members A' and A" can be tightened and released by rotating the lever 6 with respect the body 5. The body 5 has a pair of sidewalls 5a and 5b facing each other. The lever 6 has a pair of sidewalls 6a and 6b facing each other, a strap turning shaft 13 and strap pressing shaft 12 respectively extending between the pair of sidewalls 6a and 6b. The pair of links 7a and 7b respectively have first end portions pivotally connected, by means of pivot shafts 14a and 14b with the corresponding sidewalls of the lever 6 at positions externally of the lever 6, and second ends portions pivotally connected, by means of a connecting shaft 8, with the first end portions of the corresponding sidewalls 5a and 5b of the body 5 at positions internally of the body 5. The first connecting member A' has a first hook 1a connected, by means a connecting member 4, with the connecting shaft 8. The second connecting member A" includes a strap 2 having one end portion connected with a second hook 1b, and the other end portion 2a connected with the lever 6 so as to be inserted between the pair of sidewalls 6a and 6b of the lever 6 externally turned around the strap turning shaft 13 after having past the strap pressing shaft 12 and led to the outside past the strap pressing shaft 12. Accordingly, when the lever 6 is turned from a release position, as shown in FIG. 3, to a tightening position, as shown in FIGS. 1 and 2, the strap turning shaft 13 and the strap pressing shaft 12 are also turned around the pivot shafts 14a and 14b to tighten the strap 2.
The feature of the above clasping device is such that it has the pair of links 7a and 7b. Thus, when the lever 6 is rotated to the tightening position, the pivot shafts 14a and 14b move in such a direction that they sink, that is, move between the sidewalls 5a and 5b of the body, with the result that the lever 6 can be accommodated compactly inside the body 5 while the lever 6 is in the tightening position.
However, the clasping device as described above has such a disadvantage that the lever 6 can be basically rotated only one time from the release position to the tightening position, that is to say, the strap 2 can not increasingly tightened by repeatedly operating the lever 6 between the release and tightening positions more than one time. In order to increase the intensity of the tension of the strap 2, it is necessary to hold the strap 2 having been tightened by the first operation of the lever 6 so that second operation of the lever 6 can be conducted. However, it is very difficult to hold the strap 6 in a tightened manner because that the intensity of the tension given to the strap 2 is extremely large. It is to be noted that, regarding the clasping devices of this type, if the strap 2 is relatively long, the strap 2 can not be sufficiently tightened to ensure the fixing the objects.